(cis)-5,10,15,20-Tetrakis[2-(arylurea)phenyl]porphyrins: novel neutral ligands for remarkably selective and exceptionally strong chloride anion complexation in (CD3)2SO

Amplification of a thermodynamically unfavoured macrocyclic product through the directed shift of the equilibrium between dynamic covalent chemistry library members is difficult to achieve. We show for the first time that during condensation of formaldehyde and cis-N,N'-cyclohexa-1,2-diylurea formation of inverted-cis-cyclohexanohemicucurbit[6]uril (i-cis-cycHC[6]) can be induced at the expense of thermodynamically favoured cis-cyclohexanohemicucurbit[6]uril (cis-cycHC[6]). The formation of i-cis-cycHC[6] is enhanced in low concentration of the templating chloride anion and suppressed in excess of this template. We found that reaction selectivity is governed by the solution-based template-aided dynamic combinatorial chemistry and continuous removal of the formed cycHC[6] macrocycles from the equilibrating solution by precipitation. Notably, the i-cis-cycHC[6] was isolated with 33% yield. Different binding affinities of three diastereomeric i-cis-, cis-cycHC[6] and their chiral isomer (R,R)-cycHC[6] for trifluoroacetic acid demonstrate the influence of macrocycle geometry on complex formation.

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Synthesis of nickel selenites, their solubility and bonding in them

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19822069 ◽

1982 ◽

Vol 47 (8) ◽

pp. 2069-2076 ◽

Cited By ~ 10

Author(s):

Miroslav Ebert ◽

Zdeněk Mička ◽

Ilona Peková

Keyword(s):

Magnetic Properties ◽

Hydrogen Bonding ◽

Solubility Diagram ◽

Reflectance Spectroscopy ◽

Chloride Anion ◽

Fluoride Anion ◽

Infrared Absorption Spectroscopy ◽

Magnetic Parameters ◽

Nickel Cation ◽

Spectrochemical Series

The solubility diagram of the NiSeO3-SeO2-H2O system at 25 °C was studied, and on its basis, Ni(HSeO3)2.2 H2O was prepared. This selenite and NiSeO3.2 H2O were investigated by infrared absorption spectroscopy and by electronic reflectance spectroscopy and their magnetic properties were determined. Based on the infrared spectra, the force constants of the selenium-oxygen bonds were determined and the hydrogen bonding was characterized. The electronic reflectance spectra and the magnetic parameters indicate an octahedral arrangement of the coordination sphere of the nickel cation and characterize the selenite anion as a ligand that in the spectrochemical series assumes a position between the fluoride anion and water and in the nephelauxetic series, between ethylenediamine and the chloride anion.

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Crystal structure of donepezil hydrochloride form III, C24H29NO3⋅HCl

Powder Diffraction ◽

10.1017/s0885715621000415 ◽

2021 ◽

pp. 1-8

Author(s):

Joel W. Reid ◽

James A. Kaduk

Keyword(s):

Crystal Structure ◽

Density Functional Theory ◽

Powder Diffraction ◽

Density Functional ◽

Chloride Anion ◽

Powder Diffraction Data ◽

Powder Diffraction File ◽

Functional Theory ◽

Monoclinic Lattice ◽

Donepezil Hydrochloride

The crystal structure of donepezil hydrochloride, form III, has been solved with FOX using laboratory powder diffraction data previously submitted to and published in the Powder Diffraction File. Rietveld refinement with GSAS yielded monoclinic lattice parameters of a = 14.3662(9) Å, b = 11.8384(6) Å, c = 13.5572(7) Å, and β = 107.7560(26)° (C24H30ClNO3, Z = 4, space group P21/c). The Rietveld-refined structure was compared to a density functional theory (DFT)-optimized structure, and the structures exhibit excellent agreement. Layers of donepezil molecules parallel to the (101) planes are maintained by columns of chloride anions along the b-axis, where each chloride anion hydrogen bonds to three donepezil molecules each.

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